BY5.6 Cloning

Cloning

• asexual reproduction leads to genetically identical offspring
• can occur naturally in bacteria, yeast and plants grown from suckers, bulbs and corms
• artifical clones from animals produced by seperating embryos ar an early stage
• artifical clones from plants by taking cuttings and micropropagation

Embryo cloning

• makes it possible for farmers to increase the numbers of their animals
• eggs (from high milk yielding cows) fertilised in a dish by sperm from the best bulls through IVF
• fertilised egg divides to from a ball of cells
• the ball of cells 9young emrbyo) is split into separate cells
• each cell develops into a new embryo, genetically identical to the first
• embryos transplanted into surrogates
• technique conserves rare breeds

Cloning by nuclear transplant

• allows clones to be produced from one individual
• cells are taken from a donor and cultured in a medium to stop division
• infertilised egg removed from recipient and nucleus removed
• donor and recipient cells are fused together and allowed to divide, producing a ball of cells
• the developing embryo is transplanted into the womb of the surrogate
• the offspring is identical to the original donor
• technique allows for desirable qualities to be preserved for future generations

Advantages and disadvantages of animal cloning

advantages:

• cell culture is useful for the production of cells in large quantities e.g. cancer cells for medical research, monoclonal antibodies
• maintains genetic stock

disadvantages:

• in mammals it is expensive and unreliable
• may lead to the inadvertent selection of disadvantageous alleles
• progency may show unforseen effects e.g. premature aging

Tissue culture:

• technique used for growing cels in a lab
• medium that the cells are grown in are tightly controlled and conditions (e.g. water potential and temperature) are controlled fro
• used for medical and research purposes (e.g. vaccinations)

Tissue engineering

• inducing living cells to grow on a synthetic framework to produce tissue
  • replacing skin on deep burns
  • blood vessel replacement
  • bone and cartillage repair

• uses sem cells: undifferentiated cells capable of dividing to give rise to cells which can develop into different specialised cels
• have the abilty to form all…